Drum-shaped grid for a refuse incinerator



Jam 6, 1970 P. LERNER ET AL DRUM-SHAPED GRID FOR A REFUSE INCINERATOR Filed Feb. 23, 1968 2 Sheets-Sheet 1 u 4 I n I n a n u,

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DRUM-SHAPED GRID FOR A REFUSE INCINERATOR Filed Feb. 25, 1968 2 Sheets-Sheet 2 )K 7/2 66 68 B4 8O 82 MWEWMM Pam Z. FM/1? 650E655 Pare/81.0? BYM 7" firm s.

United States Patent 3,487,793 DRUM-SHAPED GRID FOR A REFUSE INCHNERATOR Paul Lerner, Montrouge, and Georges Poterlot, Pont- Sainte-Maxence, France, assignors to La Sondure Autogene Francaise Filed Feb. 23, 1968, Ser. No. 707,558 Claims priority, application France, Mar. 1, 1967, 96,918; June 7, 1967, 109,485, 109,486 Int. Cl. F23g /26; F23k 3/16, 3/10 US. Cl. 110-44 12 Claims ABSTRACT OF THE DISCLOSURE Grid for a refuse incinerator, having the shape of a drum rotating about its axis and comprising two gaspermeable surfaces, the said surfaces being affixed the one with the other and substantially parallel to each other, the said grid comprising a surface made from perforated sheet-metal, a surface constituted by grid bars and, between these two surfaces, partition elements.

Our invention relates to a drum-shaped grid for a refuse incinerator or a similar apparatus, rotating about its axis and comprising, at least over half of its length, two surfaces, which may or may not be continuous and the structure of which is gas-permeable, the said surfaces being affixecl the one with the other and substantially parallel to each other.

It is characterised in that it comprises (in order as the axis is approached):

a first surface constituted entirely or for the greater part by perforated sheet-metal or similar plate material; transverse partition elements secured to the said surface and substantially perpendicular thereto;

guided by these elements, grid bars which constitute the second surface, the space between adjacent bars ranging between 2 cm. and 15 cm. and preferably ranging between 5 and cm., each bar being preferably guided by at least three of the said elements.

Preferably, the said first surface is fixed to longitudinal partition elements which are secured to an envelope of gasdmpermeable structure, parallel to the first and to the second surface and rotating therewith.

This grid enables a combustion of the refuse or waste material which is as rapid and complete as possible. It also permits the provision of an incinerator having along working life and which is also of releatively simple construction.

In the drawings, which show, in diagrammatic form, some embodiments of the invention:

FIGURE 1 shows, in section perpendicular to its axis, an incinerator comprising a grid according to the invention, with portions shown somewhat schematically for simplicity of illustration;

FIGURE 2 shows, in perspective, a grid element according to one embodiment of the invention, in greater detail than in FIG. 1;

FIGURE 3 is a variant of FIGURE 2;

FIGURE 4 shows a portion of the incinerator of FIG- URE 1, in a partial sectional view on the line 1VIV of FIG. 1 and in greater detail than in FIG. 1.

FIGURE 1 shows an incinerator comprising a grid according to the invention.

A drum, which continuously receives the waste material and which is designated by the general reference numeral 2, rotates about its horizontal axis 4. It comprises mainly:

Externally, an envelope 6 of impermeable structure, and, on the side of the envelope directed towards the axis,

a grid having two surfaces 8, 10 of gas-permeable structure, one of the said surfaces optionally extending over a portion of the length of the drum which is shorter than the other surface; between the two surfaces 8, 10, transverse partition elements, the section of one of the said elements being designated 12; longitudinal partitions such as 14, secured to the outer surface of the grid and to the envelope 6.

Rollers such as 16, 18 support and rotate the drum about its axis.

A casing 20 channels the gases entering the drum and those leaving the drum.

The envelope 6 may be formed at one of its ends (or at both of its ends) with wide orifices establishing communication between the interior of the casing and each of the conduits comprised between the envelope, the surface 10 and two adjacent longitudinal partitions. The air entering through the inlet 22 of the casing is vigorously braked by two battles 24, 26, during its travel towards the outlet 28. It penetrates through the wide orifices; the corresponding conduits feed it under the grid, which it passes through; it also passes through. the layer 30 of refuse or other waste to be incinerated. When the gases have passed through and burnt the layer 30, they flow through the grid on the other side, follow the corresponding conduits, flow out through the wide orifices therein and are fed to a chimney via the outlet 28 in the casing. A fan may be provided for assisting the circulation of the gases.

The feeding of air into the drum may be effected in a different manner and this applies also to the evacuation of the air. It would for example be possible to cause a supplementary quantity of air to flow in through the central space at one end or at both ends of the drum; all or a part of the fumes may be extracted through the central space at One or both ends. The orifices for the inflow of air into the conduits may be formed at the end of the conduits, on the front faces of the drum, or on the side of the conduits, as shown at 66 in FIGURE 4; the same applies to the outlet for the gases.

Small-size, unburnt materials fall, through the surface 10, into the conduits where the arriving air continues their combustion and where they are mixed with the cinders. The cinders in the residues leaving the longitudinal conduits may be conveyed by a screw 32 to a discharge hopper, which also receives the incinerator residues which have remained on the surface 8.

The refuse or other waste material to be incinerated is introduced into the drum at the end thereof opposite the end at which the incinerator residues are discharged.

FIGURE 2 shows a grid element, in the case wherein the grid is constituted by elements which are individually fixed to the longitudinal partitions.

A base plate 40 formed with apertures 46 and comprising, for example, a thick, perforated plate, carries, laterally, ribs 42, 44 on which are disposed holding-down pieces. The said holding-down pieces, one end of which is shown at in FIGURE 2, provide for continuity between two juxtaposed elements, and also for the entrainment thereof; they attach the base plate 40 to the envelope 6 through the intermediary of longitudinal partitions, whilst at the same time allowing for expansion differences. The said plate constitutes the first surface having a gas-permeable structure. The apertures 46 are frustoconical, the small base being upwards in the figure. The diameter of the said small base ranges between 4 mm. and 15 mm., preferably between 6 and 10 mm. By the way of example, in the case of household refuse it would be possible to utilise a plate or sheet 8 or 12 mm. thick and formed with apertures 8 mm. in diameter at the small base and 16 mm. in diameter at the large base,

the said apertures being arranged in quincunx, with a spacing of 25 mm. between their axes.

Welded on the plate 40, perpendicular thereto, are three transverse partition elements 48, 50, 52. Grid bars, such as 54, 56, are welded to the element 52 and extend through apertures formed in the further elements, so as to make allowance for differences in expansion. The assembly comprising these bars constitutes the second permeable-structure surface. The elements 48, 50, 52 extend only slightly beyond the plane of the grid bars, but bolted or keyed behind the element 52 is an extensionpiece 58, the purpose of which it is to cause the waste material disposed on the bars to advance.

The grid bars are, for example, round iron members 14 mm, in diameter and spaced 80 mm. apart. Good results have been achieved with a free space between adjacent bars ranging from 20 to 150 mm., preferably from 50 to 100 mm.

Waste material is able to pass under the grid bars through the spaces separating the grid elements. It must not be excessively large, since the height between bars and perforated plate is approximately equal to the space between adjacent bars.

The transverse partition elements are slightly oblique relatively to the planes perpendicular to the axis of rotation of the drum; they constitute portions of an Archimedes screw directing towards the drum outlet the waste material disposed on the bars and between the latter and the perforated plate.

Practice has shown that this arrangement of the grid in two parallel surfaces whereof the one nearest the axis leaves relatively broad gaps, renders combustion more rapid and more complete. This is probably due to the fact that the bars support the waste material of larger size and a considerable proportion of the smaller waste materials, thus rendering the layer disposed on the bars more permeable.

It is unnecessary that the second surface, constituted by the bars, should extend as far as the end of the grid at which emerge the combustion residues remaining on the bars; on this side, for example in the last of the length, combustion has progressed sufficiently far to ensure that there will remain hardly any combustible pieces which are sufficiently large to prevent them from passing between the bars.

The grid bars have approximately the same length as the element with which they are associated.

The perforated plate may be welded to members constituting the ribs 42, 44 and to the partition elements 48, 50, 52. This assembly may also be constituted by a casting, which may optionally also include the extension piece 58.

The grid element according to FIGURE 3 exhibits various differences as compared with FIGURE 2.

The grid bars, such as 60, 62 are of square cross section. The bars are welded at one edge to the upper portion of all the transverse partition elements 48, 50, 52, in notches formed in the said elements; they could also be welded at a flat face. In the case of the incinerator for which grid elements of this type are intended, the temperature differences and the expansion coeflicients will not be excessive. An extension piece 64 is welded to the upper part of the element 52.

FIGURE 4 shows one end of a longitudinal partition, such as that designated by reference numeral 14 in FIG- URE l, secured to an impermeable structure envelope r0- tating with and carries a gas-permeable surface such as a base plate with apertures and grid bars (not shown). This figure is a section through a wide orifice 66 located on the side of the drum inlet; this orifice serves, alternatingly with each revolution of the drum, for the inflow of combustion air and for the outflow of fumes.

This partition is constituted by elements such as 68, 70 made of double-T section reinforced by angle members 72, 74 and by flat irons such as 76, 78 inclined in the direction providing for the urging towards the outlet of the cinders which have traversed the first surface 40 of the grid. These elements may, at their ends, displace slightly, one relatively to the other, in the direction of the partition, but they are fixed in that direction at their respecive centres. This central securing is effected in re spect of the elements 68 by a lug welded to the envelope 82. The said lug passes between the centre portion of the double-T and an extremely elongated stirrup84 welded to the said central portion. The lower flange of the double-T is recessed at this point. A second lug and a second stirrup may be provided on the other side of the element 68.

The right-hand end of the element 68 and the left-hand end of the element 70 slide, with a small clearance, between two brackets secured to the envelope; in the drawing the bracket 86 conceals the other bracket. The two brackets are identical. The bracket 86 comprises two plates 88, 90 between which a space 92 is provided; the said plates are welded to two angle irons 94, 96 which are welded to the envelope. A plate 98, which is 10 mm. thick, extends into the space 92 and also into a recess 100 in each partition element. In order to prevent the plate from being dislodged, it is folded downwardly on one side and on the other a pin extends through it. In a substantially similar manner, the left-hand end of the element 68 passes between two angle members such as 102 and the vertical displacement thereof is limited to a low value by a plate 104.

The element of the same partition located at the other end of the drum is locked in a similar manner. The intermediate elements such as 70 are secured by brackets and by lugs similar to the lug 80.

Plates such as 98, 104 prevent the lifting or lowering of the partition elements; the angle members such as 102 and the brackets prevent rocking; lugs such as 80 prevent displacement parallel to the axis.

Welded to the upper limb of the element 68 are rods 106 having a head 108 bearing on a holding-down piece 110, such as that whose one end is shown in FIGURE 2. The grid elements, only the surface of which furthest from the axis is shown, are thus secured to the longitudinal partition elements.

A heat-insulating layer 111 protects the envelope 82 from heat and diminishes the cooling of the grid and of the transverse partitions. It is one of the tasks thereof, in fact, to pre-heat the air which will burn the refuse. Furthermore, this layer prevents direct passage of the air and fumes between adjacent conduits. At the front of the apparatus, the presence of large orifices such as 66 would prevent the heat-insulation from holding firmly. Passage between adjacent conduits is prevented by battens such as 112.

The heat-insulation may be maintained, on the face thereof facing the axis, by means of a plate, not shown, which is corrugated at intervals, so as to permit expansion, and is secured to the envelope by assembly pins or studs.

What we claim is:

1. In a refuse incinerator having a radially gas-permeable drum rotatable about a horizontal axis; the improvement in which the drum comprises a sleeve of gaspermeable material, a plurality of transverse partition elements secured to the inside of the sleeve and substantially perpendicular to the portions of the sleeve to which they are secured, and a plurality of closely spaced grid bars carried by said partition elements and extending lengthwise of and spaced within the sleeve.

2. Apparatus as claimed in claim 1, said bars extending through apertures in said partition elements.

3. Apparatus as claimed in claim 2, each bar being secured to one said partition element and extending freely through at least one other partition element.

4. Apparatus as claimed in claim 1, said partition elements being disposed at acute angles to the axis of rotation of the drum thereby to constitute portions of an Archimedes screw.

5. Apparatus as claimed in claim 1, said bars being disposed in a series concentric with said gas-permeable sleeve.

6. Apparatus as claimed in claim 1, and a gas-impermeable shell concentric with and surrounding said gaspermeable sleeve, and partition elements secured to and extending lengthwise of said sleeve and said shell.

7. Apparatus as claimed in claim 6, and means fixedly securing each said longitudinal partition element to the drum intermediate its length, and slidably guiding each said partition element adjacent its ends relative to the drum.

8. Apparatus as claimed in claim 1, said sleeve being comprised of perforated metal plates.

9. Apparatus as claimed in claim 8, the perforations in said plates having a greater diameter on the radially outer side of said plates than on the radially inner side of said plates.

References Cited UNITED STATES PATENTS 2,020,960 11/1935 Pehrson et al.

2,238,161 4/1941 Drew et al. 1l0-14 2,963,996 12/1960 Uhl et a1. -14

3,408,969 11/1968 Maurice 110-14 FOREIGN PATENTS 1,494,262 1/1967 France.

KENNETH W. SPRAGUE, Primary Examiner U.S. Cl. X.R. 34--1 08 

